In this video, we're going to examine the general structure of the vertebra in the spinal column, and we'll begin with a general discussion on the overall structure of vertebra. So the vertebra will have a central area called the body. It's also called the centrum.
So this is sort of an anterior view. So here's the body. This is where the majority of the of the weight is being placed onto the vertebra. The second main component is the vertebral arch here.
The vertebral arch consists of two bone components. The pedicle, which just means little feet, and it forms this sort of little outcropping. That then connects to the lamina. So you have two pedicles, two lamina, and then they fuse together here in the medial side to form the vertebral arch.
You have this foramen here. This is known as the vertebral foramen. This is where the spine is, the spinal cord, excuse me.
And then you have little spacings. You have foramina, so both anterior and posterior to the pedicle. You have what are called intervertebral formina, so that is where you have the spinal nerve sort of exit the spinal cord.
There are seven main processes on the vertebra. You have this major process here called the spinous process, which projects posteriorly. Then you have two transverse processes. They're going to project laterally.
So these are going to be basically attachment sites for any number of muscles and ligaments, muscles to help move the vertebral column, ligaments that help stabilize the overall structure. Then you have the superior articular processes and the inferior articular processes. So these are going to protrude respectively superior and inferior. And that's happening roughly at the pedicle. Oops.
That's happening at the pedicle lamina. Junction. And usually you have these little smooth joint facets or faces.
This is going to be covered in hyaline cartilage. And basically what's going to happen is that on the inferior articular processes, You're going to have movable joints with the superior articular processes of the next vertebra. So again, allows for those sort of interactions between the vertebra. So let's examine the cervical vertebra.
So the cervical vertebra, there are seven in number. These are going to be the smallest vertebra. C1 and C2 have a very unique shape, so we'll address them individually.
But C3 to C7, they will have the very following features. So the centrum, the body will have an oval shape. When you look at the spinous process, again, flashing back, you have a very robust spinous process here.
If you look at the spinous process in the cervical vertebra, they're a little bit different. It's sort of branched, or some textbooks will call it notched. So they'll form these two little branches here.
And that's going to be the case for C3 to C6. C7 is a little bit unique in that it is not... Bifid, and in fact, instead of sort of a... Pointing sort of in a posterior fashion, it kind of prominently points towards the skin so you can actually feel the C7 vertebra's spinous process.
So the C7 vertebra is specifically known as the vertebra prominens because you are capable of palpitating it. So the vertebral foramen is going to be triangular in shape. So the shape is different between the various types of vertebra.
Additionally, you're going to have transverse foramen. That's going to be with each transverse process. So the transverse foramen is going to be of significance because this is where arteries, specifically the This is where vertebral arteries are able to pass to service the brain.
Now when we look at the type of motion that can actually happen here, I want to go over the three different types of motion that can occur in vertebra. So this isn't going to be specific to cervical, but the three types of motion that you're going to be capable of is number one, flexion and flexion and extension. So think of flexion as your ability to bend anteriorly. So we're going to say anterior bending versus posterior straightening. The second type of motion.
we're going to refer to as lateral flexion. So lateral flexion is going to be the ability to bend the upper body right or left. And then our third type of movement is going to be rotation.
So this is where one vertebra rotates against another. So again, think of flexion sort of as your ability to kind of go like this, right? And then you have flexion, bend forward, and then extension is to straighten out posteriorly. And then rotation is kind of doing this.
Okay, so when we're looking at the types of motion that occur at the cervical vertebra, this is where we have the greatest range of motion. So all three of these motions are going to be, we have the capacity to do all three of these types of motions with the cervical vertebra. Now, if we look at cervical vertebras C1 and C2, they actually sort of stray. from the general characteristics that we see with all the other vertebra.
So for example, if we look at C1, also called the Atlas, think about Atlas in Greek mythology, this was the god that was kind of holding up the world with his two hands. So if we look at the Atlas, there is no body, there is no spinous process, okay? So there are two main components.
to the atlas. The first components are these arches. So we have the posterior arch here, and then we have the anterior arch here.
And in between those two arches, we have these large sort of regions, which we're calling the lateral masses. So the lateral masses, the superior part of the lateral mass, this is where we will articulate with the occipital condyle. So that's the sort of the facet where that's going to occur. So you see the transverse foramen, again, the region where... The arteries can go to service the brain.
So the atlas has this unique shape with these little, kind of, think of landing pads for the occipital condyles, because the occipital condyles, that interaction, allows this atlas to kind of, allow us to do this kind of motion, okay? So it's associated with the head movement for yes. The axis actually has the body to the atlas, but during fetal development it fuses with the axis, doesn't stay with the atlas, and it produces this little bony outcropping called the dens.
So the dens is going to fit where the body was supposed to be. So this anterior arch region, that's where it's going to fit. And it allows the head to do the no movement.
So think about this sort of as a little hole, and here's the pin, and you can kind of rotate along that pin. So that's sort of the structure of the axis. It does have a spinous process.
And we've talked about the pedicle in the previous slide. So now we go to the thoracic vertebra. And when we look at the thoracic vertebra, as we progress downwards from T1 to T12, they progressively get larger.
And what is also unique is if you look at the spinous process, T1 and T2, The spinous process looks very similar to cervical seven's spinous process, but progressively it starts to point more and more down. So the general thoracic vertebral spinous process isn't pointing towards the skin, it's pointing down to act more as a, well, backbone. So it's pointing sort of in an inferior direction. Also interesting to note that the vertebral foramen, so that is the space where the spinal cord goes through, unlike the cervical vertebra where it was triangular in shape, here it is circular in shape.
So then we get to the articular facet. So this is where the ribs, for example, are going to articulate with these particular... vertebra.
So if we examine the structure here, you have these superior articular processes and the inferior articular process. These are in a frontal plane. Now that's quite actually significant because of its orientation. Then these particular vertebra are incapable of extension and flexion. So these vertebrae, if we're looking at the specific rotation, rotation is allowed and there is actually minimal lateral flexion allowed.
But having these processes kind of pointing in a frontal plane prevents or limits, shall we say, if I can spell correctly. It's going to limit flexion and extension. So again, think about the types of movements you're capable of with the part of your back that's directly connected to your rib cage. However, when we look at the ribs, the body actually is heart-shaped, and there's actually a face on the body, which we call the transverse costal facet. Now there's actually a superior and inferior facet that allows for different connections of the rib.
So for example, the superior transverse costal facet allows for the tubercle. of the rib to articulate while the inferior costal facet allows for the head of the rib to articulate. So moving down to the lumbar vertebra, this is the vertebra or these are the vertebra that are the largest because they receive the most stress. So there are five in number.
They have very short, very thick. pedicles and lamina. The spinous process is going to have this sort of general hatchet-like shape, very flat, and it's going to point posteriorly.
And interestingly enough, the vertebral foramen is triangular, sort of like the cervical one as well. And if you remember, when we looked at This slide up here, looking at the curvature, remember both the cervical and the lumbar curvature were concave. So it's interesting to note that both of them have a vertebral foramen that is triangular in shape. So when we look at movement, the types of movement that the lumbar vertebra are capable of, they're going to be capable of flexion and extension. There is some lateral flexion, but because of its shape, there is no rotation.
Now given the fact that there's a lot of stress here, obviously you want to further limit that by preventing the rotation. If you look at the spinous process, that thickened hatchet shape allows for the attachment of the larger back muscles as well. So the last thing I want to mention with the lumbar vertebra is when you look at the articular processes, notice how one articular process sort of nests into the other vertebra. So again, that's there to help stabilize the structure and also to prevent the rotation of one vertebra against the next.
So that leaves us with the sacrum and the coccyx. So the sacrum consists of five fused vertebrae, and the fusion happens, the sites of vertebral fusion are at these what we call transverse ridges. So the sacrum, for example, will form the posterior wall of the pelvis, and L5 will actually articulate superiorly here.
And that interaction, if we kind of, so that's L5, but the auricle surface that's located here of the sacrum, that's where you're going to sort of form interactions with the hip bones, and that forms the sacroiliac joints. Then you have sort of this almost unnecessary. coccyx, our tailbone, it doesn't serve a purpose in humans anymore, but you have three to five fused vertebrae that is going to articulate superiorly with the sacrum.